| 摘要 |
The semiconductor integrated circuit incorporates a PLL circuit including a phase-frequency comparator 1, first and second charge pumps 2 and 3, a loop filter 4, a voltage-control oscillator 5 and a divider 6. The operation mode of the PLL circuit includes a standby state where locking is stopped, a lock response operation where locking is started and a steady lock operation where the locking started by the lock response operation is continued. In the steady lock operation, setting is made so that the second charge pump 3 is smaller in charge/discharge current than the first charge pump 2. The first and second charge pumps 2 and 3 charge and discharge the loop filter 4 in response to outputs of the phase-frequency comparator 1 in reverse to each other in phase. In the lock response operation where locking is started, the second charge pump 3 is stopped from charging and discharging in reverse in phase.
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